1/* Compute lookahead criteria for bison,
2
3   Copyright (C) 1984, 1986, 1989, 2000, 2002, 2004, 2006-2007,
4   2009-2012 Free Software Foundation, Inc.
5
6   This file is part of Bison, the GNU Compiler Compiler.
7
8   This program is free software: you can redistribute it and/or modify
9   it under the terms of the GNU General Public License as published by
10   the Free Software Foundation, either version 3 of the License, or
11   (at your option) any later version.
12
13   This program is distributed in the hope that it will be useful,
14   but WITHOUT ANY WARRANTY; without even the implied warranty of
15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16   GNU General Public License for more details.
17
18   You should have received a copy of the GNU General Public License
19   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
20
21#ifndef LALR_H_
22# define LALR_H_
23
24# include <bitset.h>
25# include <bitsetv.h>
26
27/* Import the definition of RULE_T. */
28# include "gram.h"
29
30/* Import the definition of CORE, TRANSITIONS and REDUCTIONS. */
31# include "state.h"
32
33
34/** Build the LALR(1) automaton.
35
36   Find which rules need lookahead in each state, and which lookahead
37   tokens they accept.
38
39   Also builds:
40     - #goto_map
41     - #from_state
42     - #to_state
43     - #goto_follows
44*/
45void lalr (void);
46
47/**
48 * Set #nLA and allocate all reduction lookahead sets.  Normally invoked by
49 * #lalr.
50 */
51void initialize_LA (void);
52
53/**
54 * Build only:
55 *   - #goto_map
56 *   - #from_state
57 *   - #to_state
58 * Normally invoked by #lalr.
59 */
60void set_goto_map (void);
61
62/**
63 * Update state numbers recorded in #goto_map, #from_state, and #to_state such
64 * that:
65 *   - \c nstates_old is the old number of states.
66 *   - Where \c i is the old state number, <tt>old_to_new[i]</tt> is either:
67 *     - \c nstates_old if state \c i is removed because it is unreachable.
68 *       Thus, remove all goto entries involving this state.
69 *     - The new state number.
70 */
71void lalr_update_state_numbers (state_number old_to_new[],
72                                state_number nstates_old);
73
74
75/** Release the information related to lookahead tokens.
76
77   Can be performed once the action tables are computed.  */
78void lalr_free (void);
79
80typedef size_t goto_number;
81# define GOTO_NUMBER_MAXIMUM ((goto_number) -1)
82
83/** Index into #from_state and #to_state.
84
85   All the transitions that accept a particular variable are grouped
86   together and GOTO_MAP[I - NTOKENS] is the index in FROM_STATE and
87   TO_STATE of the first of them.  */
88extern goto_number *goto_map;
89
90/** The size of #from_state and #to_state.  */
91extern goto_number ngotos;
92
93/** State number which a transition leads from.  */
94extern state_number *from_state;
95
96/** State number it leads to.  */
97extern state_number *to_state;
98
99/** Map a state/symbol pair into its numeric representation.  */
100goto_number map_goto (state_number s0, symbol_number sym);
101
102/* goto_follows[i] is the set of tokens following goto i.  */
103extern bitsetv goto_follows;
104
105
106#endif /* !LALR_H_ */
107